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Clarify the difference between text and binary files. I'm not sure the 

tutorial is the right place to mention a file object's encoding.
This commit is contained in:
Skip Montanaro 2007-09-26 01:10:12 +00:00
parent 5dde61d0b9
commit 4e02c503e7
1 changed files with 14 additions and 8 deletions
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Doc/tutorial/inputoutput.rst
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@ -197,14 +197,20 @@ automatically added to the end. ``'r+'`` opens the file for both reading and
writing. The *mode* argument is optional; ``'r'`` will be assumed if it's
omitted.
On Windows and the Macintosh, ``'b'`` appended to the mode opens the file in
binary mode, so there are also modes like ``'rb'``, ``'wb'``, and ``'r+b'``.
Windows makes a distinction between text and binary files; the end-of-line
characters in text files are automatically altered slightly when data is read or
written. This behind-the-scenes modification to file data is fine for ASCII
text files, but it'll corrupt binary data like that in :file:`JPEG` or
:file:`EXE` files. Be very careful to use binary mode when reading and writing
such files.
``'b'`` appended to the mode opens the file in binary mode, so there are
also modes like ``'rb'``, ``'wb'``, and ``'r+b'``. Python distinguishes
between text and binary files. Binary files are read and written without
any data transformation. In text mode, platform-specific newline
representations are automatically converted to newlines when read and
newline characters are automatically converted to the proper
platform-specific representation when written. This makes writing portable
code which reads or writes text files easier. In addition, when reading
from or writing to text files, the data are automatically decoded or
encoding, respectively, using the encoding associated with the file.
This behind-the-scenes modification to file data is fine for text files, but
will corrupt binary data like that in :file:`JPEG` or :file:`EXE` files. Be
very careful to use binary mode when reading and writing such files.
.. _tut-filemethods: